SLOS823D December 2012 – March 2020 THS4531A
PRODUCTION DATA.
The circuit shown in Figure 70 is used to measure the frequency response of the amplifier.
A network analyzer is used as the signal source and the measurement device. The output impedance of the network analyzer is 50 Ω and is AC coupled. RIT and RG are selected to impedance match to 50 Ω and maintain the proper gain. To balance the amplifier, a 49.9-Ω resistor and blocking capacitor to ground is inserted across RIT on the alternate input.
The output is routed to the input of the network analyzer through 50-Ω coax. For a 2k load, 38 dB is added to the measurement to refer back to the output of the amplifier according to Table 5.
For output impedance, the signal is injected at VOUT with VIN left open. The voltage drop across the 2x RO resistors is measured with a high impedance differential probe and used to calculate the impedance into the output of the amplifier.